Diatoms Inspired Green Janus Fabric for Efficient Fog Harvesting

Fog harvesting is a promising path against the global freshwater scarcity. Asymmetric wettability fabric-based fog collection materials inspired by the Namib desert beetle have been reported widely due to their easy access and adjustable structures. Nevertheless, the single drive force for water transportation produced by the asymmetric wettability is insufficient, causing a non-ideal fog harvesting efficiency. Moreover, sustainability challenges persist for fog collection materials, primarily due to their heavy dependence on chemical treatments. Herein, a diatom-inspired Janus fabric (Ly/Csp-3) based on asymmetric wettability and aperture gradient is developed without additional physical or chemical treatment. The wettability gradient and aperture gradient generate dual directional drive forces that regulate the water transport direction more accurately and enhance the transportation rate more effectively. Ly/Csp-3 reaches a one-way transport index of 390.7% and a water collecting rate (WCR) of 1170.5 mg cm⁻² h⁻¹, while exhibiting the capability of anti-acid rain and the resistance to sunlight. This work provides an efficient and programmable biomimetic design proposal for fibrous fog harvesting devices.